Process for the preparation of cephalosporin c intermediates

ABSTRACT

THIS INVENTION RELATES TO THE CHEMICAL SYNTHESIS OF CEPHALOSPORIN C LACTONE BY A PROCESS THAT UTILIZES A NOVEL INTERMEDIATE HAVING THE FORMULA I   3-(R1-N(-R2)-C(-COO-R3)=CH-N-),4-(R4-S-CH2-)FURAN-2(3H)-   ONE   WHEREIN R1 AND R2 TOGETHER FORM A DIVALENT ACYL GROUP DERIVED FROM DICARBOXYLIC ACID; R3 IS ALKYL, ARYL, ARALKYL; AND R4 IS ACYL, ALKYL, OR ARALKYL; AND THE PROCESS OF PREPARATION THEREOF.

United States Patent 01 fice 3,592,810 PROCESS FOR THE PREPARATION OF CEPHALOSPORIN C INTERMEDIATES Joseph E. Dolfini, North Brunswick, NJ., assignor to E. R. Squibb & Sons, Inc., New York, N.Y. N Drawing. Filed June 16, 1967, Ser. No. 646,484 Int. Cl. C07d 99/24 US. Cl. 260-240 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the chemical synthesis of cephalosporin C lactone by a process that utilizes a novel intermediate having the Formula I wherein R and R together form a divalent acyl group derived from dicarboxylic acid; R is alkyl, aryl, aralkyl; and R is acyl, alkyl, or aralkyl; and the process of preparation thereof.

This invention relates to a process for the preparation of cephalosporin C lactones. More particularly, this invention relates to the preparation of intermediates having Formula I HZN- S O- (L (II) According to the present invention, it has been discovered that surprisingly high yields of the intermediate having the structure of Formula I may be prepared by reacting an aminobutenolide of Formula III I i E HZNA/W wherein R is as defined herein with an aminomalonaldehydic acid ester of Formula IV wherein R R and R are as hereinabove defined.

The initial step of this invention, i.e., the reaction of an a-aminobutenolide with an acylated aminomalonalde- Patented July 13, 1971 of about 25 C. to about C., preferably at ambient temperatures to about 80 C. in an inert organic solvent, such as lower alcohol (ethanol or hexanol), a non-polar aromatic solvent (e.g., benzene and toluene) or others, such as nitromethane or chloroform. These solvents may also be utilized throughout the invention.

Once the intermediate product of Formula I is obtained, it may be treated with an acid, such as trifiuoroacetic, hydrogen chloride or borontrifluoride under temperatures in the range of 30 C. to about 80 C. in an organic solvent, such as those listed above to yield a dihydrothiazine compound of Formula V 0 (v) wherein R R and R are as defined herein.

The compound of Formula V may also be formed by adding an acid catalyst, e.g., hydrogen chloride, sulfuric acid, borontrifluoride, trifluoroacetic, and so forth, to the solvent system in the initial step of the invention.

The products of Formula V may then by cyclized to 7- acylaminocephalosporanic lactone acid compounds of Formula VI N S ail wherein R and R are as defined herein by treating them with reagents such as mesityl Grignard reagents, organozinc reagents, e.g., dimethyl zinc or methyl zinc iodide, and alkyl aluminums e.g., tri-(isobutyl)aluminum.

In addition, Compounds V may be converted to products of Formula VII Ala- 7 NH (VIII) at reaction temperatures in the range of -15 C. to

. +15 C. Removal of the phthaloyl group may be effected hydic acid, is carried on under temperatures in the range by utilizing hydrazine at ambient temperatures to provide a compound (IX) which, as according to the teachings in C. R. Acad., Se. Paris, (7/11/66), is an intermediate to the synthesis of cephalosporin C lactones.

Examples of aminobutenolides that may be utilized in the practice of the instant invention are: a-amino-fl-tritylthiomethyl-A -butenolide; a amino-benzylthiomethyl-A butenolide; a-amino-t-butylthiomethyl-A -butenolide; aamino-acetylthiomethyl-A -butenolide, and so forth.

Among the amino-malonaldehydic acid esters that may be utilized in the practice of this invention are: t-butyla phthalimidomalonaldehydate; methyl a phthalimidomalonaldehydate; and other like esters as disclosed and prepared in accordance with the teachings in US. Pat. No. 3,231,571, patented Jan. 25, 1966.

The following examples are illustrative of this invention. All temperatures are in degrees centigrade unless otherwise stated:

EXAMPLE 1 a-[[[2,5 dihydro 2 ox-4-[(tritylthio)methyl]-3- furyl]amino]methylene] 1,3 dioxo 2 isoindolineacetic acid, methyl ester (A) TRANS ISOMER A solution of 247 mg. (1 mmol) methyl a-phthalimidomalonaldehydic ester and 387 mg. (1 mmol) a-amino-[itritylthiomethyl-A -butenolide and mg. p-toluenesulfonic acid monohydrate in 30 ml. benzene was refluxed for one hour using a Dean Stark trap to isolate water of reaction. A dry powder was obtained after removing solvent at reduced pressure; upon trituration with 5 ml. cold acetonitrile crystalline material was obtained, 440 mg., M.P. 2l2213 C. A further 160 m.g., M.P. 211- 215 C., could be obtained from the mother liquor by concentrating and chilling. A total of 700 mg. (97%) was obtained of the trans isomer.

(B) CIS ISOMER.

A solution of 247 mg. (1 mmol) methyl a-phthalimidomalonaldehydic ester and 387 mg. (1 mmol) a-amino-fitritylthiomethyl-A -butenolide in ml. 3:1 methanol: chloroform was acidified to congo red with methanolic HCl and stirred for one hour at room temperature. The residue obtained after removal of the solvent at reduced pressure was triturated with 5 ml. cold methanol giving 587 mg. (95%) of white crystals, M.P. 224-224 C. of the cis isomer.

EXAMPLE 2 1,2,5 ,7-tetrahydro-u-phthalimido-7-oxo-4H-furo 3,4-d] [1,3]-thiazine-2-acetic acid, methyl ester A suspension of 1.00 g. (1.62 mmol) cis unsaturated ester (from example 1 (B); the trans isomer from 1 (A) may also be used) in 200 ml. nitromethane was treated with a rapid stream of hydrogen chloride gas for fifteen minutes at room temperature after which the resulting solution was stirred for forty-five minutes more at ambient temperature before removal of the solvent at reduced pressure. The crude semisolid obtained was taken up in benzene and washed onto 80 g. florisil (100/200 mesh). Elution with 400 ml. benzene removed a quantitative yield of triphenyl carbinol; elution with 1 1. chloroform removed the product as 583 mg. (96%) of a glass which crystallized from methanol to provide 425 mg. (70%) of product, M.P. 212-2l4 C. The isomeric compound remained in the mother liquors and was obtained only as an oil.

EXAMPLE 3 3- [hydroxymethyl] -8-oxo-6-phthalimido-5-thia-l-azabicyclo[4.2.0]-oct2-ene-2-carboxylic acid, -lactone A solution of 374 mg. (1 mmol) of the dihydrothiazinemethyl carboxylic ester from Example 2 in 20 ml. dry xylene is treated with 0.33 ml. of a 1 molar solution of triisobutyl aluminum in zylene at room temperature under nitrogen for forty-eight hours. The zylene solution is then diluted with 100 ml. benzene, washed with 50 ml. 1% aqueous acetic acid, then 50 ml. 5% aqueous sodium bicarbonate; dried over sodium sulfate, decanted, and solvent removed at reduced pressure. The fi-lactam can be obtained by chromatography on alumina or fractional crystallization.

Use of the second, oily isomer cited in Example 2, leads to an isomeric fl-lactam in same fashion.

EXAMPLE 4 1,2,5 ,7-tetrahydro-u-phthalimido-7-oxo-4H-furo- [3,4-d] [1,3]-thiazine-2-acetic acid (A) A solution of 578 mg. (0.2 mmol) t-butyl aphthalimidomalonaldehydic ester and 774 mg. (0.2 mmol) a-amino-B-tritylthiomethyl-A -butenolide in 50 ml. benzene was refluxed for 2.5 hours, the water of reaction being removed by a Dean Stark trap. Upon removal of the solvent at reduced pressure an amorphous powder, the crude unsaturated t-butyl ester was deposited. The total crude intermediate was taken up in nitromethane (40 ml.) and cooled to -20 C., the solution was treated with a rapid stream of hydrogen chloride gas for ten minutes at this temperature, stirred ten minutes longer and diluted with ml. chloroform precooled to 0 C. The resulting solution was evaporated at below room temperature. The crude product was taken up in ml. chloroform and extracted with excess aqueous 5% sodium bicarbonate. Acidification of the aqueous extracts followed by chloroform extraction led to the isolation of 441 mg. (61%) of the crude acid. The crude acid could be separated into two racemates dec. pt. 178180 C., and 208-210 C. by fractional crystallization from chloroform or acetone-water.

(B) 1,2,5,7 tetrahydro-a-phthalimido-7-oxo-4H-furo- [3,4-d] [1,3]-thiazine-2-acetic acid, t-butyl ester: The neutral layer in Example 4 (A) was dried over sodium sulfate, decanted and evaporated. Chromatography on 409 florisil (100/200 mesh) gave triphenyl carbinol in benzene eluant followed by the t-butyl ester as a mixture of two isomers in the chloroform eluant. The t-butyl esters crystallized from chloroform/ hexane and could be separated by fractional chromatography. The amount of t-butyl ester isolated can be increased by lowering the temperaturet of the reaction in Example 4(A).

(C) A one molar solution of the carboxylic acid mixture in Example 4(A) in nitromethane containing a catalytic amount of BF or HCl was converted to the mixture of the corresponding t-butyl esters by passing isobutylene into the solution at room temperature or below.

EXAMPLE 5 A 0.10 molar solution of either carboxylic acid (from 4(C)) in nitromethane reacts with a 5% excess of dicyclohexylcarbodiimide to provide the corresponding ,8- lactams. Added triethylamine catalyzes the reaction. The lactams are crystalline compounds (chloroform/hexane) and are isolated by filtering, then evaporating the nitromethane solution.

The invention may be variously otherwise embodied within the scope of the appended claims.

What is claimed is: 1. A compound having the formula:

wherein R is as defined in claim 1, with an aminomalonaldehydic acid ester of the formula \NCHCHO wherein R R and R are as defined in claim 1 in the presence of an acid.

4. A process in accordance with claim 3 wherein the aminobutenolide is 0: amino fl tritylthiomethyl A butenolide.

5. A process in accordance with claim 3 wherein the aminomalonaldehydic acid is t-butyl-u-phthalimidomalonaldehydic ester.

References Cited FOREIGN PATENTS 2/1962 France 260243 OTHER REFERENCES JOHN D. RANDOLPH, Primary Examiner U.S. Cl. X.R.

10-11150 UNITED PATENT OFFICE CERTIFICATE 0E CORRECTION am: No. 92,810 Dam] July 13. 1971 Inventor) Joseph E. Dolfini It is certified that error appears in the above-identified patent and that said Latter. Patent arc hereby corrected 0 shown below:

Column 1, first formula .1

1 4 L R\ CH SR 1 2 4 1 should be:

N CCH N I R I 3 O R I 3 Q0 12 00 R fourth formula, 4 I R I I S g h 151 b s on e:

CH 1 CH 2 2 H N- O: O O== O Column 3, line 2, "Se." should be 5a.;

line 42, "m.g.," should be mg.;

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3'592'8lO Dated y 7 Invantm-(a) Joseph E. Dolfini PAGE 2 It is certified that error appears in the above-identified patent And that said Letters Patent are hereby corrected a sham bulov:

s s I c should be: 2

HZN H 2 O O O 0 Signed and sealed this 11th day of April' 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

ROBERT GO Attesting Office TTSCHALK Commissioner of Patents 

